Why is my SSL certificate not working?
Common Causes
SSL certificate problems often stem from simple issues like expiration, where the certificate has passed its validity date and needs renewal. Another frequent cause is a domain name mismatch: the certificate was issued for a different domain (e.g., www vs non-www) or subdomain than the one you're using.
Incorrect installation can also break SSL. This includes missing intermediate certificates, wrong file paths, or server configuration errors. Additionally, if your server is behind a CDN or proxy, SSL might terminate there and not reach your origin correctly.
- Expired certificate: Renew it immediately.
- Domain mismatch: Ensure the certificate covers all variations (www, non-www, subdomains).
- Missing intermediate certificates: Install the full chain.
- Server misconfiguration: Check SSL settings in your web server (e.g., Apache, Nginx).
- Mixed content: Some resources on your page load over HTTP, causing browser warnings.
How to Diagnose
Use online SSL checkers like SSL Labs' SSL Test or Why No Padlock to identify specific errors. These tools show certificate details, chain issues, and mixed content problems.
Check your server's error logs for SSL handshake failures. If you recently moved servers or changed DNS, allow time for propagation. For detailed steps, consult your hosting provider's documentation.
Common mistakes
- Assuming SSL is working just because the padlock appears; browsers may still show warnings for mixed content.
- Forgetting to renew before expiration; set up auto-renewal where possible.
- Installing only the domain certificate without the intermediate chain, causing trust issues on some devices.
